150 MICROSOMAL PARTICLES 



average chain length as calculated from Van Slyke amino nitrogen determina- 

 tions any amino acid should be N terminal 1.5 per cent of the time and should 

 follow the tryptic cut about 14 per cent of the time. 



Failure to observe these ratios indicates one of two situations: either there 

 are statistical rules of sequence, or a small number of protein species con- 

 tributes a large fraction of the total protein mass. Recent results reported on 

 the column separation of E. coli proteins [7] indicate that the protein mass 

 is distributed with reasonable uniformity among a large number of proteins or 

 protein groups. Thus, the results presented in table 1 suggest that statistical 

 rules of sequence are operative in specifying E. coli proteins. 



REFERENCES 



1. H. F. Gaines, Cryptanalysis, Dover 5. Fraenkel-Conrat et al., Methods of 

 Publications, Inc., 1956. Biochem. Anal, 2, 399 (1955). 



2. R. B. Roberts et al., Studies of Bio- g. H . J. Morowitz and M. Spaulding, 

 synthesis in Escherichia coli, Carnegie Inst. Biochim. et Biophys. Acta, in press. 

 Wash Publ. 607, Washington, D. C, 1955 ? Work reported in ^ yolume by 



3. G. Gamow et al., Advances in Biol. . 



and Med. Phys., 4, 23 (1956). workers at Carne g ie Institution of Wash- 



4. C. B. Anfinsen and R. R. Redfield, ington, Department of Terrestrial Mag- 

 Advances in Protein Chem., 11, 1 (1956). netism. 



